Provided herein are descriptions of methods and systems for the use and application of RF communication devices integrated with light sources for position detection of mobile devices, control of a lighting system, and for communication with mobile and stationary devices, preferably in spaces of relatively limited extent (e.g., retail store interiors, convention floors, libraries, airport terminals, roofed sports stadiums, courtyards) that are illuminated by lights capable of communicating information by visible light communication (VLC). In various embodiments, these methods and systems enable the RF communications devices to enhance and support the position-determination function and other functions of a system or network of one or more VLC-capable lights. Also in various embodiments, these methods and systems advantageously co-locate the RF communications devices with VLC lights powered by standard mains lighting power, obviating the use of batteries or the installation of special wiring to power the RF communications devices.
Indoor positioning services relate to systems and methods whereby the locations of mobile devices and their users within buildings are estimated. Such services may be based on various physical modalities, including light, radio waves, ultrasonic waves, and floor vibrations. Indoor positioning is a key component of location-aware computing, which relates to applications that utilize the location of a mobile device to provide the device's user with content relevant to their location. Some location-aware computing functions pertain to entertainment, marketing, and management. An example of an entertainment function supported by indoor positioning is augmented reality, technology that functionally overlays a virtual space onto a physical space. Marketing functions supported by indoor positioning include advertising and content distribution through mobile devices (e.g., tablets, cell phones, wearable computers, smart tags). Herein, “marketing” refers to content distribution even in nonprofit settings. Indoor marketing functions differ importantly from those for off-site environments: for example, for a retail enterprise, indoor marketing can include unique aspects such as alerting a customer via their mobile device of discounts on items in the store. In an example, a customer not in the store sees an ad in general media for a product at a given location. They then travel to that location. Upon entry they are prompted by a radio-frequency (RF) capability of the store's lighting network to view their mobile device. This exposes the mobile device to ambient light and enables visible light communication (VLC)-supported position estimation for the device. The customer is then alerted to a special discount coupon, available to them at that time only, for a product in the store, and may interact with a map displayed on their device that employs the device's VLC position estimate and directs them to the product. In general, in-store content and ad distribution capabilities are enabled by indoor location services that are not feasible in the prior art.
An illustrative management function for indoor positioning is inventory navigation: e.g., in a warehouse, the indoor positioning system can direct a person equipped with a mobile device to where a particular item is located. Inventory tracking is also possible: e.g., if the person removes the item (an event that may be either logged by the device user on their mobile device, or automatically detected as motion of an electronic tag on the item), a back-end server can update inventory databases to reflect this change.
In another exemplary management function, a mobile device using a light-based indoor position positioning technique in conjunction with a wireless connection (e.g., WiFi) can enable non-intrusive data collection on customers. For example, data collection on how customers move through a store and where they spend time can be collected and used to improve layout and merchandise displays.
Light-based indoor positioning systems have various advantages over systems employing other physical modalities. Signals from Global Positioning System (GPS) satellites, often used for determining the location of mobile computing devices, lose significant power when passing through construction materials and suffer from multi-path propagation effects, making GPS unsuitable for indoor navigation. Techniques based on received signal strength indication (RSSI) from radio transceivers (e.g., WiFi and Bluetooth wireless access points) have been explored for indoor positioning, but positioning accuracy of RSSI-based systems is limited to the multi-meter range. Ultrasonic techniques, which transmit inaudible acoustic waves to microphones, can also be used to approximate indoor position; however, ultrasound tends to be more limited in range than radio and commonplace devices and networks are not configured for communicating via ultrasound.
VLC indoor positioning techniques employ optical signals, either visible or infrared, typically emitted by lights also performing an illumination function, and can be used to accurately locate mobile devices indoors. Optical techniques are more accurate and/or reliable than other approaches: since light waves are highly directional and do not pass through most materials, a light-detecting device can be presumed proximate to a light source if the source is robustly detectable. Moreover, many mobile devices are inherently equipped with cameras that may be exploited for optical indoor positioning, and are simultaneously in contact via radio with one or more communications networks (e.g., telephone, Internet). Herein, “mobile devices” includes all portable devices having a computational capability (e.g., phones, tablets, wearable computers, electronic tags, etc.). Also, light-based indoor positioning systems are easy and low-cost to set up: e.g., to install, a building operator may need only to swap out existing bulbs for VLC bulbs. No new socket hardware or power wiring is required, and no scheduled battery maintenance need be instituted.
However, optical indoor positioning techniques have several limitations or drawbacks. For example, VLC signals cannot be sent or received directly by many computing devices or networks (e.g., servers, the cell phone network, the Internet); standardized protocols do not exist for the exchange of data, commands, and other information between VLC beacons and other computing devices or networks; VLC signals are not detectable by devices lacking light sensors or whose light sensors are not exposed to ambient light (e.g., a cell phone stowed in a user's pocket); the bandwidth of VLC beacons is low relative to that of various other communications modalities; and, because of the tendency of light to be attenuated by even flimsy objects, any intercommunicating network of VLC devices (e.g., ceiling lights in a retail space) would likely be unreliable and subject to isolation of portions of the network by architectural or other barriers. All of these drawbacks, as well as others not named, arise from the innate character of VLC signaling. Techniques are therefore desired by which the advantageous aspects of VLC indoor positioning may be combined with those of one or more other communications modalities. Also desired are methods for remote control, monitoring, and diagnosis of a lighting network that may feature non-VLC lights and/or VLC lights.